She's the British Greta Garbo. He's a New York artist who partied with Andy Warhol and Patti Smith. Philip Hoare asks Duncan Hannah about his unlikely muse, the reclusive Nova Pilbeam

In a quiet house in a leafy street somewhere in north London, a lady of certain years keeps receiving letters from an American artist, asking the colour of her eyes. "I'm thinking they're blue", he writes. But he never gets a reply from Nova Pilbeam.

At 14, Pilbeam was a child star; at 19, a Hitchcock blonde. She was, for a few short years, a home-grown British screen goddess; our Greta Garbo. But like Garbo, she cut short her glamorous career in the 1940s, and since 1948, Nova Pilbeam hasn't been seen on screen. Her life, once so public, has become entirely private. "She was an iconic figure," says that American artist, Duncan Hannah, as he tries to explain his obsession with this now little-known and long- forgotten star. "It was because she was obscure that I liked her. She belongs to me. She's all mine."

Even as I call Hannah at his Upper West-side studio in Manhattan, he is at work on five new studies of Pilbeam. He has painted her countless times. "The strange thing is that those are the paintings which always sell first," he says. "People seem to respond to her. I think they like the fact that I'm obsessed. They're buying part of the obsession. They don't even know who she is." In fact, people often assume that he made her up.

This is understandable. Hannah's paintings are mysterious compositions. They almost always feature vintage imagery: Brooklands-style racing cars, art deco Odeon cinemas, country houses which look as though they were last tenanted by Ivor Novello. The figures that populate them are schoolboys in shorts or starlets in gowns; their faces seem both familiar and strange. A diver is caught in the act of diving; a naked girl poses full-length. Like Edward Hopper's painting, there's a quiet, surreal theatricality to Hannah's works, an unspoken narrative, as if the viewer is left to supply the words. The New York Sun saw Hannah's paintings as " Brideshead Revisited meets Enid Blyton meets the quirky, tonal aloofness of Walter Richard Sickert". But what is even more extraordinary is that they are the work of a man who hung out with the New York Dolls in the 1970s, who boasted Andy Warhol as a mentor, and who once gave his cat to Patti Smith.

Duncan Hannah's interest in Nova Pilbeam was aroused when he saw her in Young and Innocent, her second film for Alfred Hitchcock, made at Pinewood Studies in 1937. "I was a Hitchcock fan, and I hadn't seen this one", Hannah recalls. "She was 17 years old in it. I just feel in love with her. I kept watching it - I saw it 12 times." Then he began to paint her, again and again; the fresh-faced, very English actress had become a kind of ghostly muse for the American. A friend managed to get her address, and so he began to write, too. Every time he painted her, he would send her a catalogue with her picture in it. "Never heard anything," he says. The one-sidedness of the relationship just made things all the more elusive. "She's the plucky English schoolgirl," rhapsodises Hannah. "She's got such spunk. That iconic face."

Born in Wimbledon in 1919, Pilbeam's career moved quickly from stage school to a starring role in Little Friend - a 1934 film with a screenplay by Christopher Isherwood. The movie broke box-office records, and audiences' hearts. "Even at that time," Hitchcock said of the child-star, "she had the intelligence of a fully grown woman. She had plenty of confidence and ideas of her own."

Nova was still only 15 when Hitchcock cast her in The Man Who Knew Too Much. In Shepperton Babylon, his essential survey of British cinema, Matthew Sweet describes Pilbeam as "a wholesome blonde with dark, accusing eyebrows like Tenniel's Alice". Young and Innocent (1937) is "a love story - but unusually for Hitchcock, it's the sweetest sort of movie," says Hannah. "A young couple are pursued by the police, and fall in love." During the filming of Young and Innocent, Pilbeam met and fell in love with Hitchcock's assistant director, Penrose Tennyson. He was a "good-looking, restless, steely young man" with left-wing sympathies - he also happened to be the great-grandson of Alfred Lord Tennyson. They married on the eve of war, in 1939, and Tennyson was all set to become a great British director in his own right.

But as Matthew Sweet also observes, accounts of Tennyson's brief life "glow with that burnished, Homeric quality common to all stories of privileged young man felled in battle". In July 1941, Tennyson was killed in a plane crash in the Scottish highlands. His death seemed to deprive Nova of the desire to act. She appeared fitfully afterwards - notably a documentary shot by Jill Craigie, wife of Labour Party leader, Michael Foot - but generally her image seemed to recede from the spotlight... only to be revived, decades later, by an American painter.

Duncan Hannah's own career is hardly less interesting. Born in New York state in 1952, he trained as a painter at Parsons School of Design in NYC in 1973. It was a heady time: "The Dolls were king." Glammed up in their own retro-drag mix - the link between Roxy Music and the Sex Pistols - the New York Dolls created an entire scene around them. It was a transitional era, with its own nostalgia for the 1920s and 1930s, reinvented through a futuristic, if not apocalyptically decadent lens, and Hannah was part of it.

It's fascinating to walk the streets of Greenwich Village and the Lower Eastside with Hannah and hear him point out the places of pilgrimage: the site of Warhol's Factory, bars where the Dolls played residencies. When CBGBs opened in 1974, Hannah recalls, "There were about 10 people there, and I was one of them. My friends were Blondie, Televison, Talking Heads. "I met all my childhood heroes: Nico, Brian Eno, Patti Smith. It was a very decadent time. By 1976 it had become full-blown punk. It was sort of a strange period for a visual artist."In that time of flux and shifting pop aesthetics, anyone could do anything.

Hannah diversified into acting, co-starring in two art-house movies with Debbie Harry in Unmade Beds (1976), and The Foreigner (1977). He also worked for Andy Warhol's Interview. He took Warhol to see the Talking Heads. "Andy kept saying, 'Oh, they're so cute. Gee. We must get them back to the Factory'. So we did, and we interviewed them, and I did the photo session, directed by Andy."

Like others who knew Warhol, Hannah doesn't subscribe to the notion of the artist as vampire, as suggested by the recent Edie Sedgwick biopic, Factory Girl. "He was very supportive of me. Interview were very good to me. They even ran one of my paintings on the 'Table of Contents', and Mick Jagger rang up Andy and asked to buy it. Andy was like Santa Claus to me. I'd say, 'I'm trying to paint like Balthus', and Andy would say, 'Oh, what a great idea. I must do that." He even proposed that they trade works. "He said, 'I'll do your portrait, then I'll take equal value in your paintings." Sadly, this barter was not to bear fruit: Warhol died two weeks later.

Hannah's first group exhibition, The Times Square Show in 1980, launched his career as a fine artist. "It was all these underground people, Keith Haring and so on. We rented a massage parlour in Times Square. The press paid a lot of attention." The next show, New York New Wave (1981), featured work by David Byrne and Brian Eno. "Everything moved so fast," Hannah recalls, "from a massage parlour to an East 57th gallery in three months. It had been tough being a painter in the 1970s. It seemed an obsolete form. Suddenly it was the right thing to do." Since then Hannah's work has featured on book covers for William Boyd, Anthony Burgess, Patrick McGrath and John Banville. He exhibits regularly in New York and elsewhere, but next month sees only his second London show, at the Rebecca Hossack gallery in Fitzrovia. Inevitably, the star will be Nova Pilbeam.

Naturally, she has been invited; whether she will turn up is another matter. Matthew Sweet also tried to interview Pilbeam for his book, "to no avail. Eventually she stopped answering my sycophantic letters. She's extremely reticent - I think because of the circumstances in which she lost her husband and her career." Sweet did consider staking out her house, but perhaps wisely, decided against it.

Nor is Hannah sure that he wants to meet his heroine. "In my head she is always 19. I don't know what it would be like to meet her now - I have pieced her together from those bits of celluloid." Hannah's fantasy Nova - his version of Warhol's Marilyn - is as much a product of his idealised pre-war England as Warhol's was a comment on post-war America. Raised by anglophile parents, he was "taught that England was the place," he says. "It became a sort of mythical place in my imagination. England is not quite a real place to me." Part of that admiration extends to its Pop Art practitioners, Peter Blake, Ron Kitaj, David Hockney, who tend to be more humorous and wry than their glossy American equivalents.

Hannah looks the part, too. When I met him last year in the Century Association in New York he was wearing sports jacket, tie and Oxford brogues, a cross between Jay Gatsby and Charles Ryder, perfectly at home in this hushed and grand New York equivalent of a Pall Mall gentlemen's club.

Yet when I rang him for this piece, he enthusiastically reported having seen Iggy Pop and the Stooges the night before in Harlem; "Iggy got his cock out, as usual." In Legs Mc-Neill's seminal 1996 book, Please Kill Me: The Uncensored Oral History of Punk, Hannah is much quoted, a deadpan voice telling tales of getting picked up by Lou Reed. In the accompanying archive photo, his angelic features resemble nothing so much as the languid self-portrait with which Truman Capote shocked readers on the dust jacket of his first novel, Other Voices, Other Rooms. Yet Hannah now lives happily ensconced with the accomplished book designer, Megan Wilson, and they weekend with two cats and a huge library in their clapboard cottage in Connecticut.

A paradox, then, Mr Hannah; a rock 'n' roll survivor in tweeds, a man to whom the past segues into itself. Characteristically, of his new show, he quotes from a 1938 Jean Gabin film, Port of Shadows, in which a dissolute French artist says: "I painted flowers, women and children. It's like I painted the crime right into them. I'd see crime in a rose. It's because there's someone or something hidden behind that rose. I can't help painting what's hidden behind things. To me a swimmer is already a drowned man." But most hidden of all are the enigmatic features of Nova Pilbeam, whose painted eyes still give little away.